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<FONT color="green">001</FONT>    package org.apache.commons.net.ntp;<a name="line.1"></a>
<FONT color="green">002</FONT>    /*<a name="line.2"></a>
<FONT color="green">003</FONT>     * Licensed to the Apache Software Foundation (ASF) under one or more<a name="line.3"></a>
<FONT color="green">004</FONT>     * contributor license agreements.  See the NOTICE file distributed with<a name="line.4"></a>
<FONT color="green">005</FONT>     * this work for additional information regarding copyright ownership.<a name="line.5"></a>
<FONT color="green">006</FONT>     * The ASF licenses this file to You under the Apache License, Version 2.0<a name="line.6"></a>
<FONT color="green">007</FONT>     * (the "License"); you may not use this file except in compliance with<a name="line.7"></a>
<FONT color="green">008</FONT>     * the License.  You may obtain a copy of the License at<a name="line.8"></a>
<FONT color="green">009</FONT>     *<a name="line.9"></a>
<FONT color="green">010</FONT>     *      http://www.apache.org/licenses/LICENSE-2.0<a name="line.10"></a>
<FONT color="green">011</FONT>     *<a name="line.11"></a>
<FONT color="green">012</FONT>     * Unless required by applicable law or agreed to in writing, software<a name="line.12"></a>
<FONT color="green">013</FONT>     * distributed under the License is distributed on an "AS IS" BASIS,<a name="line.13"></a>
<FONT color="green">014</FONT>     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.<a name="line.14"></a>
<FONT color="green">015</FONT>     * See the License for the specific language governing permissions and<a name="line.15"></a>
<FONT color="green">016</FONT>     * limitations under the License.<a name="line.16"></a>
<FONT color="green">017</FONT>     */<a name="line.17"></a>
<FONT color="green">018</FONT>    <a name="line.18"></a>
<FONT color="green">019</FONT>    <a name="line.19"></a>
<FONT color="green">020</FONT>    import java.io.IOException;<a name="line.20"></a>
<FONT color="green">021</FONT>    import java.net.DatagramPacket;<a name="line.21"></a>
<FONT color="green">022</FONT>    import java.net.InetAddress;<a name="line.22"></a>
<FONT color="green">023</FONT>    <a name="line.23"></a>
<FONT color="green">024</FONT>    import org.apache.commons.net.DatagramSocketClient;<a name="line.24"></a>
<FONT color="green">025</FONT>    <a name="line.25"></a>
<FONT color="green">026</FONT>    /***<a name="line.26"></a>
<FONT color="green">027</FONT>     * The NTPUDPClient class is a UDP implementation of a client for the<a name="line.27"></a>
<FONT color="green">028</FONT>     * Network Time Protocol (NTP) described in RFC 1305 as well as the<a name="line.28"></a>
<FONT color="green">029</FONT>     * Simple Network Time Protocol (SNTP) in RFC-2030. To use the class,<a name="line.29"></a>
<FONT color="green">030</FONT>     * merely open a local datagram socket with &lt;a href="#open"&gt; open &lt;/a&gt;<a name="line.30"></a>
<FONT color="green">031</FONT>     * and call &lt;a href="#getTime"&gt; getTime &lt;/a&gt; to retrieve the time. Then call<a name="line.31"></a>
<FONT color="green">032</FONT>     * &lt;a href="org.apache.commons.net.DatagramSocketClient.html#close"&gt; close &lt;/a&gt;<a name="line.32"></a>
<FONT color="green">033</FONT>     * to close the connection properly.<a name="line.33"></a>
<FONT color="green">034</FONT>     * Successive calls to &lt;a href="#getTime"&gt; getTime &lt;/a&gt; are permitted<a name="line.34"></a>
<FONT color="green">035</FONT>     * without re-establishing a connection.  That is because UDP is a<a name="line.35"></a>
<FONT color="green">036</FONT>     * connectionless protocol and the Network Time Protocol is stateless.<a name="line.36"></a>
<FONT color="green">037</FONT>     *<a name="line.37"></a>
<FONT color="green">038</FONT>     * @author Jason Mathews, MITRE Corp<a name="line.38"></a>
<FONT color="green">039</FONT>     * @version $Revision: 489397 $ $Date: 2006-12-21 16:28:51 +0000 (Thu, 21 Dec 2006) $<a name="line.39"></a>
<FONT color="green">040</FONT>     ***/<a name="line.40"></a>
<FONT color="green">041</FONT>    <a name="line.41"></a>
<FONT color="green">042</FONT>    public final class NTPUDPClient extends DatagramSocketClient<a name="line.42"></a>
<FONT color="green">043</FONT>    {<a name="line.43"></a>
<FONT color="green">044</FONT>        /*** The default NTP port.  It is set to 123 according to RFC 1305. ***/<a name="line.44"></a>
<FONT color="green">045</FONT>        public static final int DEFAULT_PORT = 123;<a name="line.45"></a>
<FONT color="green">046</FONT>    <a name="line.46"></a>
<FONT color="green">047</FONT>        private int _version = NtpV3Packet.VERSION_3;<a name="line.47"></a>
<FONT color="green">048</FONT>    <a name="line.48"></a>
<FONT color="green">049</FONT>        /***<a name="line.49"></a>
<FONT color="green">050</FONT>         * Retrieves the time information from the specified server and port and<a name="line.50"></a>
<FONT color="green">051</FONT>         * returns it. The time is the number of miliiseconds since<a name="line.51"></a>
<FONT color="green">052</FONT>         * 00:00 (midnight) 1 January 1900 UTC, as specified by RFC 1305.<a name="line.52"></a>
<FONT color="green">053</FONT>         * This method reads the raw NTP packet and constructs a &lt;i&gt;TimeInfo&lt;/i&gt;<a name="line.53"></a>
<FONT color="green">054</FONT>         * object that allows access to all the fields of the NTP message header.<a name="line.54"></a>
<FONT color="green">055</FONT>         * &lt;p&gt;<a name="line.55"></a>
<FONT color="green">056</FONT>         * @param host The address of the server.<a name="line.56"></a>
<FONT color="green">057</FONT>         * @param port The port of the service.<a name="line.57"></a>
<FONT color="green">058</FONT>         * @return The time value retrieved from the server.<a name="line.58"></a>
<FONT color="green">059</FONT>         * @exception IOException If an error occurs while retrieving the time.<a name="line.59"></a>
<FONT color="green">060</FONT>         ***/<a name="line.60"></a>
<FONT color="green">061</FONT>        public TimeInfo getTime(InetAddress host, int port) throws IOException<a name="line.61"></a>
<FONT color="green">062</FONT>        {<a name="line.62"></a>
<FONT color="green">063</FONT>            // if not connected then open to next available UDP port<a name="line.63"></a>
<FONT color="green">064</FONT>            if (!isOpen())<a name="line.64"></a>
<FONT color="green">065</FONT>            {<a name="line.65"></a>
<FONT color="green">066</FONT>                open();<a name="line.66"></a>
<FONT color="green">067</FONT>            }<a name="line.67"></a>
<FONT color="green">068</FONT>    <a name="line.68"></a>
<FONT color="green">069</FONT>            NtpV3Packet message = new NtpV3Impl();<a name="line.69"></a>
<FONT color="green">070</FONT>            message.setMode(NtpV3Packet.MODE_CLIENT);<a name="line.70"></a>
<FONT color="green">071</FONT>            message.setVersion(_version);<a name="line.71"></a>
<FONT color="green">072</FONT>            DatagramPacket sendPacket = message.getDatagramPacket();<a name="line.72"></a>
<FONT color="green">073</FONT>            sendPacket.setAddress(host);<a name="line.73"></a>
<FONT color="green">074</FONT>            sendPacket.setPort(port);<a name="line.74"></a>
<FONT color="green">075</FONT>    <a name="line.75"></a>
<FONT color="green">076</FONT>            NtpV3Packet recMessage = new NtpV3Impl();<a name="line.76"></a>
<FONT color="green">077</FONT>            DatagramPacket receivePacket = recMessage.getDatagramPacket();<a name="line.77"></a>
<FONT color="green">078</FONT>    <a name="line.78"></a>
<FONT color="green">079</FONT>            /*<a name="line.79"></a>
<FONT color="green">080</FONT>             * Must minimize the time between getting the current time,<a name="line.80"></a>
<FONT color="green">081</FONT>             * timestamping the packet, and sending it out which<a name="line.81"></a>
<FONT color="green">082</FONT>             * introduces an error in the delay time.<a name="line.82"></a>
<FONT color="green">083</FONT>             * No extraneous logging and initializations here !!!<a name="line.83"></a>
<FONT color="green">084</FONT>             */<a name="line.84"></a>
<FONT color="green">085</FONT>            TimeStamp now = TimeStamp.getCurrentTime();<a name="line.85"></a>
<FONT color="green">086</FONT>    <a name="line.86"></a>
<FONT color="green">087</FONT>            // Note that if you do not set the transmit time field then originating time<a name="line.87"></a>
<FONT color="green">088</FONT>            // in server response is all 0's which is "Thu Feb 07 01:28:16 EST 2036".<a name="line.88"></a>
<FONT color="green">089</FONT>            message.setTransmitTime(now);<a name="line.89"></a>
<FONT color="green">090</FONT>    <a name="line.90"></a>
<FONT color="green">091</FONT>            _socket_.send(sendPacket);<a name="line.91"></a>
<FONT color="green">092</FONT>            _socket_.receive(receivePacket);<a name="line.92"></a>
<FONT color="green">093</FONT>    <a name="line.93"></a>
<FONT color="green">094</FONT>            long returnTime = System.currentTimeMillis();<a name="line.94"></a>
<FONT color="green">095</FONT>            // create TimeInfo message container but don't pre-compute the details yet<a name="line.95"></a>
<FONT color="green">096</FONT>            TimeInfo info = new TimeInfo(recMessage, returnTime, false);<a name="line.96"></a>
<FONT color="green">097</FONT>    <a name="line.97"></a>
<FONT color="green">098</FONT>            return info;<a name="line.98"></a>
<FONT color="green">099</FONT>        }<a name="line.99"></a>
<FONT color="green">100</FONT>    <a name="line.100"></a>
<FONT color="green">101</FONT>        /***<a name="line.101"></a>
<FONT color="green">102</FONT>         * Retrieves the time information from the specified server on the<a name="line.102"></a>
<FONT color="green">103</FONT>         * default NTP port and returns it. The time is the number of miliiseconds<a name="line.103"></a>
<FONT color="green">104</FONT>         * since 00:00 (midnight) 1 January 1900 UTC, as specified by RFC 1305.<a name="line.104"></a>
<FONT color="green">105</FONT>         * This method reads the raw NTP packet and constructs a &lt;i&gt;TimeInfo&lt;/i&gt;<a name="line.105"></a>
<FONT color="green">106</FONT>         * object that allows access to all the fields of the NTP message header.<a name="line.106"></a>
<FONT color="green">107</FONT>         * &lt;p&gt;<a name="line.107"></a>
<FONT color="green">108</FONT>         * @param host The address of the server.<a name="line.108"></a>
<FONT color="green">109</FONT>         * @return The time value retrieved from the server.<a name="line.109"></a>
<FONT color="green">110</FONT>         * @exception IOException If an error occurs while retrieving the time.<a name="line.110"></a>
<FONT color="green">111</FONT>         ***/<a name="line.111"></a>
<FONT color="green">112</FONT>        public TimeInfo getTime(InetAddress host) throws IOException<a name="line.112"></a>
<FONT color="green">113</FONT>        {<a name="line.113"></a>
<FONT color="green">114</FONT>            return getTime(host, NtpV3Packet.NTP_PORT);<a name="line.114"></a>
<FONT color="green">115</FONT>        }<a name="line.115"></a>
<FONT color="green">116</FONT>    <a name="line.116"></a>
<FONT color="green">117</FONT>        /***<a name="line.117"></a>
<FONT color="green">118</FONT>         * Returns the NTP protocol version number that client sets on request packet<a name="line.118"></a>
<FONT color="green">119</FONT>         * that is sent to remote host (e.g. 3=NTP v3, 4=NTP v4, etc.)<a name="line.119"></a>
<FONT color="green">120</FONT>         *<a name="line.120"></a>
<FONT color="green">121</FONT>         * @return  the NTP protocol version number that client sets on request packet.<a name="line.121"></a>
<FONT color="green">122</FONT>         * @see #setVersion(int)<a name="line.122"></a>
<FONT color="green">123</FONT>         ***/<a name="line.123"></a>
<FONT color="green">124</FONT>        public int getVersion()<a name="line.124"></a>
<FONT color="green">125</FONT>        {<a name="line.125"></a>
<FONT color="green">126</FONT>            return _version;<a name="line.126"></a>
<FONT color="green">127</FONT>        }<a name="line.127"></a>
<FONT color="green">128</FONT>    <a name="line.128"></a>
<FONT color="green">129</FONT>        /***<a name="line.129"></a>
<FONT color="green">130</FONT>         * Sets the NTP protocol version number that client sets on request packet<a name="line.130"></a>
<FONT color="green">131</FONT>         * communicate with remote host.<a name="line.131"></a>
<FONT color="green">132</FONT>         *<a name="line.132"></a>
<FONT color="green">133</FONT>         * @param version the NTP protocol version number<a name="line.133"></a>
<FONT color="green">134</FONT>         ***/<a name="line.134"></a>
<FONT color="green">135</FONT>        public void setVersion(int version)<a name="line.135"></a>
<FONT color="green">136</FONT>        {<a name="line.136"></a>
<FONT color="green">137</FONT>            _version = version;<a name="line.137"></a>
<FONT color="green">138</FONT>        }<a name="line.138"></a>
<FONT color="green">139</FONT>    <a name="line.139"></a>
<FONT color="green">140</FONT>    }<a name="line.140"></a>




























































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